There is a temp-sensor switch on top of the engine next to the fuel filter, jumper the two wires and the fan should go on. This is the hot-engine mode.

Jumper the high-pressure switch on the A/C dryer and they should come on low speed, if not then there is a ceramic resistor nearby that often fails.

Check also to be sure that they turn freely. It sounds like they might be freewheeling from the airflow when you're revving the engine.

__________________

Gone to the dark side

- Jeff